Green Party MP and Petone resident Holly Walker has confirmed she is pregnant, telling her followers on Twitter that "the cat’s out of the bag".

The 30-year-old MP released a poster drawn up by friends yesterday, highlighting several photos of a bump on her belly and asking, "Is Holly hiding something?"

Walker, a Rhodes Scholar and former student newspaper editor, entered Parliament following the 2011 election.

While the posts did not disclose when Walker is due to give birth, one of the photos of the bump was taken when the anti-asset sale petition was presented to Parliament on March 12, almost two months ago.

The pregnancy is not the only one of the current term, with Labour’s Nanaia Mahuta, the MP for Hauraki-Waikato, giving birth to her second child in December.